Agroecological zone is a zone which has a unique combination of physiographic, soil, hydrological and agroclimatic characteristics. Thirty agroecological zones (AEZ), 88 sub-zones (sub-regions) and 535 agroecological units have been identified in Bangladesh on the basis of important differences in physiography, soil, hydrological and agroclimatic characteristics. Agroecological zoning helps classify regions where a particular crop may or may not be grown.

Physiography is the combination of geological material in which, a particular kind of soils have formed and the landscape on which they occur. It is the primary element in defining and delineating the agroecological regions of Bangladesh. Bangladesh can be divided into three broad physiographic regions. The percentage composition of these three physiographic regions are as follows:

Physiographic region and percentage

1. Northern and Eastern Tertiary hills 12%

2. Pleistocene terraces 8%

3. Recent flood plains 80%

a. Old Himalayan Piedmont Plain

b. Tista Floodplain

      i. Active Tista Floodplain

      ii. Tista Meander Floodplain

c. Karatoya-Bangali Floodplain

d. Lower Atrai Basin

e. Lower Punarbhaba Floodplain fo Brahmaputra Floodplain

     i. Active Brahmaputra-Jamuna Floodplain

     ii. Young Brahmaputra and Jamuna Floodplain

      iii. Old Buahmaputra Floodplain

g. Ganges River Floodplain

      i. Active Ganges Floodplain

      ii. High Ganges River Floodplain

      iii. Low Ganges River Floodplain

h. Ganges Tidal Floodplain

        i Ganges Tidal Floodplain (Non-Saline)

       ii. Ganges Tidal Floodplain (Saline)

       iii. Ganges Tidal Floodplain (Sunderbans)

i. Gopalganj-Khulna Bils

j. Arial Bil

k. Meghna River Floodplain

     i. Middle Meghna River Floodplain

     ii. Lower Meghna River Floodplain

l. Meghna Estuarine Floodplain

       i. Young Meghna Estuarine Floodplain (Non-Saline)

      ii. Young Meghna Estuarine Floodplain (Saline)

      iii. Old Meghna Estuarine Floodplain

m. Surma-Kushiyara Floodplain

       i. Eastern Surma-Kushiyara Floodplain

       ii. Sylhet Basin n. Northern and Eastern Piedmont Plains

o. Chittagong Coastal Plain

p. St. Martins Coral Island

q. Barind Tract

      i. Level Barind Tract

      ii. North-eastern Barind Tract

       iii. High Barind Tract

r. Madhupur Tract

s. Northern and Eastern Hills

      i. High Hill Ranges

      ii. Low Hills

t. Akhaura Terrace